Vehicle Wire Overheat Protection Using Solar-Aware Temperature Estimation
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Solution Overview
Problem
Existing overheat protection systems for vehicle wire harnesses face challenges in accurately estimating environmental temperatures, leading to errors in current interruption and potential overheating or sudden current interruption issues.
Innovation Solution
A vehicle control device that includes a current detecting unit, a current interrupting unit, and a computing unit. The computing unit calculates the temperature rise in the lead wire using the current detection value and estimates the environmental temperature by combining this value with outside air temperature, inside air temperature, and solar radiation information, thereby determining whether to interrupt the current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fuse is used for overheat protection, then the wire harness can be protected against overcurrent, but the system requires manual replacement of the fuse and uses thicker wire harnesses, increasing weight and cost
Solution Approach 1:
The patent replaces the mechanical fuse system with a semiconductor switch-based electronic protection system. The semiconductor switch (MOSFET) electronically interrupts overcurrent based on temperature estimation from current detection, eliminating the need for physical fuses and thicker wire harnesses, thereby reducing weight while maintaining protection reliability
Solution Approach 2:
The system uses the wire harness itself to detect its own temperature rise through current monitoring and thermal estimation algorithms. The control unit calculates temperature based on detected current values and thermal characteristics, enabling the system to self-diagnose and self-protect without external sensors or manual intervention
2Device complexity
If the reference temperature is set to inside air temperature, then the system is simple to implement, but the environmental temperature estimation is inaccurate in shielded spaces affected by solar radiation
Solution Approach 1:
The patent introduces solar radiation information as an intermediary factor to bridge the gap between easily measurable inside air temperature and the actual environmental temperature in shielded spaces. By incorporating solar radiation data into the temperature estimation algorithm, the system accurately calculates the environmental temperature without requiring physical temperature sensors in difficult-to-access locations
Solution Approach 2:
The system dynamically adjusts the reference temperature parameter based on solar radiation conditions. Instead of using a fixed inside air temperature, the control unit modifies the reference temperature by adding a solar radiation-induced temperature rise component, enabling accurate environmental temperature estimation that reflects actual thermal conditions in shielded wire harness spaces
3Strength
If the wire harness is installed in a shielded space, then the wiring is protected physically, but the environmental temperature estimation becomes inaccurate due to solar radiation heat inflow
Solution Approach 1:
The patent applies different thermal characteristics to different locations of the wire harness system. It recognizes that shielded spaces have unique thermal properties due to solar radiation accumulation, and adjusts the temperature estimation algorithm specifically for these locations by incorporating solar radiation information, rather than using a uniform temperature model for all wire harness locations
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution enables accurate estimation of lead wire temperatures, ensuring appropriate current interruption and preventing overheating, while also reducing the weight and cost of the wire harness by eliminating the need for thicker wire harnesses.
Implementation Method 1
a current detecting unit that detects a current flowing through a lead wire
Implementation Method 2
computes a temperature rise value caused by Joule heat in the lead wire using the current detection value
Data Source
AI summary
A vehicle control device includes: a current detecting unit for detecting a current flowing through a lead wire, and outputting a current detection value; a current interrupting unit for interrupting the current flowing through the lead wire; and a computing unit for computing a temperature rise value caused by Joule heat in the lead wire using the current detection value, estimating an environmental temperature of an environment in which the lead wire is wired based on the temperature rise value, outside air temperature information of a vehicle, inside air temperature information in a vehicle cabin, and solar radiation information, and determining whether to output a current interruption instruction to the current interrupting unit based on the temperature of the lead wire estimated using the environmental temperature.